Hi,
I am aware that the general consensus is
- Just move on. Put your energies into your next guest. It happens.
- For the sake of your fellow hosts, review him succinctly, honestly and unemotionally.
We have hosted more than 1000 guests over the past 5 years. unfortunately we are still suffering from a 1 star review that we received in 2014, not sure how the averages are calculated but even though we have 100s 5star reviews (and very rarely receive 4*) we are still 4.6 
Reservation was for 4 guests. These guests booked our large townhouse (entire place) with a 70% discount on our standard rates also a 5% weekly discount + bnb no refund discount 20-25% (I do realise the total is > 100% but we did get some money, which was effectively about 30% of the rate we set. donāt know how these are calculated by bnb)
So I completely agree with the OP about Promotions, Bargain-Hunters and Star Ratings
Unfortunately there is so much competition there is no way we can even break even without these huge discounts believe you me we have tried 
also we work VERY VERY hard, for a very small amount of money, I am sure this will be familiar to those who are trapped in the hosting business.
Since the time they arrived they were pointing out issues, then after staying for 3 nights they reported an issue in the bathroom, to which we responded literally within 5 minutes and arranged a plumber to visit in 2 hours time. The plumber advised that the toilet flange has to be replaced along with the drainage pipe, which might have been damaged. These repairs were going to take 2 days so it was an emergency where we had to cancel the reservation via airbnb and refund the guests. we informed the guests also bnb CSR called them and informed them of the situation, cancelled the remainder of their stay. it all went smoothly unto that point.
They weird things started to happen, there was no indication of them packing to leave, their stuff was all over the house. So they waited and waited for about another 4-5 hours. Bnb CSR sent them a list of alternative accommodation options.
They they said āI am sorry but we are not leaving because we have things in the fridge!!!ā (a pint of milk and another bottle) they didnāt have a reservation at this point b/c the reservation was cancelled by bnb and a refund issued. The plumber was scheduled to visit to repair in a couple of hours time. We tried to explain them that itās not safe to use the house b/c the drainage pipe might have burst and the seal had to replaced in the toilet. But they completely refused to accept these safety concerns and continued to stay.
We had to insist that they leave the house and that we are happy to arrange a free taxi to their chosen destination. But they simply refused to leave and started getting violent saying that we are bad people and we were doing this to serve our own interests! (which really was confusing bc we followed up on their complaints and tried to ensure safety for the guests even though we lost out 2-3 days of rental b/c we had to block the house for repairs and pay for the repairs etc). They kept insisting that they stay the night even though there were 300+ other places available for they entire stay starting from that night and we had refunded the remainder of the stay. At this stage they invited us to call the police, banged own house door in our face, and drew the curtains and barricaded in our house when they no longer had a reservation with us!!!
We messaged BNB CSR and explained that we might have to call the police. This standoff went on for about another hour, then time was around 7pm they finally came out, and agreed to leave (guessing the BNB CSR spoke to them?). So we arranged a free taxi for them and even helped they load their bags to the taxi.
So yes we work like servants and butlers to our bnb guests :(, staying up all night, answering the stupidest questions 24x7 within 5 minutes of receiving. Receive each and every group of guests personally with a welcome drink, sweets, maps etc spend at least 30-45 mins with them showing the place, answering questions etc. Our rates for this large town house are sometimes a lot less than one would pay for a hotel room 200 meters away.
Now they have left a review, which I am 99% sure is very negative. Just stressed out about this b/c a negative review might influence the bnb algorithm when displaying our house to potential guests. We do have VRBO but itās only about 5% of bookings.
How would you write a review?
How would you handle this type of a rude guests?
Are we in the wrong? we simply followed a protocol where we got a professional assessments and then tried to fix issues.
Sorry for the long post, writing this has been cathartic sorry for the non native English.
(But that is my point of view, with over 600 reviews and a 4.7 average I do not care about a lesser review)